#include <cstdio> #include <algorithm> #include <cstring> using namespace std; int n, arr[50005], save[50005]; int tmp[50005]; long long maxx, minn; const int inf = 0x7fffffff; inline int read() { int s = 0, f = 1; char ch = getchar(); while (ch < '0' || ch > '9') { if (ch == '-') f = -1; ch = getchar(); } while (ch >= '0' && ch <= '9') s = s * 10 + ch - '0', ch = getchar(); return s * f; } int cmpa(int a, int b) { return a < b; } int cmpb(int a, int b) { return a > b; } void inserta(int * arr, int tot, int key) { for (int i = tot; i >= 0; --i) { if (arr[i] > key) arr[i + 1] = arr[i]; else { arr[i + 1] = key; break; } } } void insertb(int * arr, int tot, int key) { for (int i = tot; i >= 0; --i) { if (arr[i] < key) arr[i + 1] = arr[i]; else { arr[i + 1] = key; break; } } } void show(int * r, int n) { for (int i = 1; i <= n; ++i) { printf("%d ", r[i]); } puts(""); } int main() { n = read(); for (int i = 1; i <= n + 1; ++i) arr[i] = read(); memcpy(save, arr, sizeof(arr)); sort(arr + 1, arr + 1 + n, cmpa); for (int i = n; i >= 3; --i) { for (int j = 1; j <= i - 2; ++j) tmp[j] = arr[j + 2]; inserta(tmp, i - 2, arr[1] * arr[2] + 1); for (int j = 1; j <= i - 1; ++j) arr[j] = tmp[j]; } maxx = arr[1] * arr[2] + 1; memcpy(arr, save, sizeof(arr)); sort(arr + 1, arr + n + 1, cmpb); for (int i = n; i >= 3; --i) { for (int j = 1; j <= i - 2; ++j) tmp[j] = arr[j + 2]; tmp[0] = inf; insertb(tmp, i - 2, arr[1] * arr[2] + 1); for (int j = 1; j <= i - 1; ++j) arr[j] = tmp[j]; } minn = arr[1] * arr[2] + 1; printf("%lld\n", maxx - minn); return 0; }